A1 responds to ____ sounds as well is real ones.
The auditory system requires ____ for full development.
In people who are deaf from birth, the axons leading to the ____ ____ develop less than in other people.
Where is damaged area V1 leaves someone blind, damage to the area A1 does not produce ____.
People with damage to the ____ ____ ____ hear simple sounds reasonably well, unless the damage extends into subcortical brain areas.
primary auditory cortex
The main deficiency for people with damage to the primary auditory cortex is in the ability to recognise ____ or ____ of sounds, like music or speech. Evidently, the cortex is not necessary for all hearing, only for advanced processing of it.
combinations or sequences
When researchers record from cells in the primary auditory cortex while playing pure notes, they find that each cell has a preferred tone. The auditory cortex provides a kind of map of the sounds. Researchers call it a ____ map.
In alert, waking animals, each cell in area A1 responds to its ____ sound and hardy responds at all to other sounds.
Surrounding the primary auditory cortex are additional ____ areas.
Cells outside area A1 respond best to what we might call auditory "____" – sounds such as animal cries, machinery noises, music, and other identifiable, meaningful sounds.
We distinguish two categories of hearing impairment: ____ deafness and ____ deafness.
conductive : nerve
Diseases, infections, or tumourous bone growth can prevent the middle ear from transmitting soundwaves properly to the cochlea. The result is ____ ____, or middle-ear deafness.
Because people with conductive deafness have a ____ cochlea and auditory nerve, they hear their own voices, which can be conducted through the bones of the skull directly to the cochlea, bypassing the middle ear. Because they hear themselves clearly, they may blame others for talking too softly.
____ ____, or inner-ear deafness, results from damage to the cochlea, hair cells, or the auditory nerve.
Nerve deafness can be inherited, or it can develop from a variety of ____, including: Exposure of the mother to rubella, syphilis, or other diseases or toxins during pregnancy. Inadequate oxygen to the brain during birth. Deficient activity in the thyroid gland. Certain diseases, including multiple sclerosis and meningitis. Childhood reaction to certain drugs, including aspirin. Exposure to loud noises.
Researchers have found that exposure to ____ ____ produces long-term damage to the synapses and neurons of the auditory system that doesn't always show up on hearing tests. It might eventually lead to ringing in the ears, extreme sensitivity to noise, or other problems.
Nerve deafness often produces ____ – frequent or constant ringing in the ears. In some cases, tinnitus is due to a phenomenon like phantom limb.
Damage to part of the cochlea is like an ____: if the brain no longer gets its normal input, axons representing other parts of the body may invade a brain area previously responsive to sounds, especially high-frequency sounds.
Some people find they can increase or change their tinnitus by clenching their jaw or tensing their neck muscles. Presumably axons representing the jaw and neck ____ their auditory cortex.
____ ____ is less accurate than visual localisation, but nevertheless impressive. You can identify a sound direction even if it occurs just briefly or while you are turning your head.
Determining the direction and distance of a sound requires ____ the responses of the two ears.
One cue for location is the difference in intensity between the ears. For high-frequency sounds, with a wavelength shorter than the width of the head, it creates a ____ ____ making the sound louder for the closer ear.
Another method is the difference in ____ of ____ at the two ears. Time of arrival is most useful for localising sounds with a sudden onset.
time of arrival
A third cue is the ____ ____ between the ears.
Humans ____ low-frequencies by phase differences and high-frequency by loudness differences. We ____ a sound of any frequency by its time of onset if it occurs suddenly enough.
All methods of sound localisation require ____, because the distance between the two ears changes during childhood as the head grows larger.